public class Example4_20 {
  public static void main(String args[]) {
   char a[] = {'a','b','c','D','E','F'};
   for(int i = 0;i<a.length;i++) {
     if(Character.isLowerCase(a[i]))
       a[i] = Character.toUpperCase(a[i]);
     else if(Character.isUpperCase(a[i]))
       a[i] = Character.toLowerCase(a[i]);
     }
     for(int i=0;i<a.length;i++)
       System.out.print(" "+a[i]);
     }
}
